support/support_path_support_time64.c

   1 /* Check if path supports 64-bit time interfaces.
   2    Copyright (C) 2021 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <fcntl.h>
  20 #include <support/check.h>
  21 #include <support/support.h>
  22 #include <sys/stat.h>
  23 #ifdef __linux__
  24 #include <sysdep.h>
  25 #endif
  26
  27 #ifdef __linux__
  28 static int
  29 utimesat_call (const char *path, const struct __timespec64 tsp[2])
  30 {
  31 # ifndef __NR_utimensat_time64
  32 #  define __NR_utimensat_time64 __NR_utimensat
  33 # endif
  34   return syscall (__NR_utimensat_time64, AT_FDCWD, path, &tsp[0], 0);
  35 }
  36 #endif
  37
  38 bool
  39 support_path_support_time64 (const char *path)
  40 {
  41 #ifdef __linux__
  42   /* Obtain the original timestamps to restore at the end.  */
  43   struct statx ostx;
  44   TEST_VERIFY_EXIT (statx (AT_FDCWD, path, 0, STATX_BASIC_STATS, &ostx) == 0);
  45
  46   const struct __timespec64 tsp[] =
  47   {
  48     /* 1s and 2s after y2038 limit.  */
  49     { 0x80000001ULL, 0 },
  50     { 0x80000002ULL, 0 }
  51   };
  52   /* Return is kernel does not support __NR_utimensat_time64.  */
  53   if (utimesat_call (path, tsp) == -1)
  54     return false;
  55
  56   /* Verify if the last access and last modification time match the ones
  57      obtained with statx.  */
  58   struct statx stx;
  59   TEST_VERIFY_EXIT (statx (AT_FDCWD, path, 0, STATX_BASIC_STATS, &stx) == 0);
  60
  61   bool support = stx.stx_atime.tv_sec == tsp[0].tv_sec
  62                  && stx.stx_mtime.tv_sec == tsp[1].tv_sec;
  63
  64   /* Reset to original timestamps.  */
  65   const struct __timespec64 otsp[] =
  66   {
  67     { ostx.stx_atime.tv_sec, ostx.stx_atime.tv_nsec },
  68     { ostx.stx_mtime.tv_sec, ostx.stx_mtime.tv_nsec },
  69   };
  70   TEST_VERIFY_EXIT (utimesat_call (path, otsp) == 0);
  71
  72   return support;
  73 #else
  74   return true;
  75 #endif
  76 }